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Inserting air into hot glass to form a bubble has been used to make glass objects since Roman times. In new work, researchers apply these same glass blowing principles on a microscopic scale to make specialized miniature cone-shaped lenses known as axicons.
Axicons are used to shape laser light in a way that is beneficial for optical drilling, imaging and creating optical traps for manipulating particles or cells. These lenses have been known for more than 60 years, but their fabrication, especially when small, is not easy.
Technique - Potential - Miniature - Axicons - Glass
"Our technique has the potential of producing robust miniature axicons in glass at a low cost, which could be used in miniaturized imaging systems for biomedical imaging applications, such as optical coherence tomography, or OCT," said research team member Nicolas Passilly from FEMTO-ST Institute in France.
In The Optical Society (OSA) journal Optics Letters, the researchers describe the new fabrication approach, which is based on the same processes used to make large numbers of photonic and electronic circuits in parallel on semiconductor wafers. The researchers used their approach to create glass axicons with diameters of 0.9 and 1.8 millimeters and showed that they successfully generated Bessel beams.
Microfabrication - Axicons - Microsystems - Wafer-level - System
"Wafer-level microfabrication allows the axicons to be integrated into more complex microsystems created also at a wafer-level, leading to a system made of a wafer stack," said Passilly. "This type of integration comes with better optical alignments, high performance vacuum packaging and much lower-costs for the final systems because a large number can be processed simultaneously."
When used with a laser, axicons create a beam of light that begins as a Bessel-like beam—a non-diffracting beam with maximum intensity on its axis—and then turns into a hollow beam further away from the axicon. Bessel-like beams feature a depth of field that can be orders of magnitude larger than that of a beam...
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